Re: [PATCH] tpm, tpm_tis: fix TPM 2.0 probing

From: Stefan Berger
Date: Tue Feb 10 2015 - 07:16:41 EST


On 02/09/2015 03:39 AM, Jarkko Sakkinen wrote:
On Mon, Feb 09, 2015 at 12:08:46AM +0100, Peter Hüwe wrote:
Am Mittwoch, 4. Februar 2015, 15:21:09 schrieb Jarkko Sakkinen:
If during transmission system error was returned, the logic was to
incorrectly deduce that chip is a TPM 1.x chip. This patch fixes this
issue. Also, this patch changes probing so that message tag is used as the
measure for TPM 2.x, which should be much more stable.
Is it aware that some TPMs may respond with 0x00C1 as TAG for TPM1.2 commands?
I guess none of the TPM 1.2 command answer with the tag 0x8002?


FYI: pdf page 26 , section 6.1 explains the predictable return value for a TPM1.2 command seen by a TPM2

http://www.trustedcomputinggroup.org/files/static_page_files/8C68ADA8-1A4B-B294-D0FC06D3773F7DAA/TPM%20Rev%202.0%20Part%203%20-%20Commands%2001.16-code.pdf

Following this:

Sending a TPM1.2 command to a TPM2 should return a TPM1.2 header (tag = 0xc4) and error code (TPM_BADTAG = 0x1e)

Sending a TPM 2 command to a TPM 2 will give a TPM 2 tag in the header.
Sending a TPM 2 command to a TPM 1.2 will give a TPM 1.2 tag in the header and an error code.


Stefan

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/